The proposed program for the next grant period consists of: (1) A study of the activity of the enzymes glutathione reductase, glutathione peroxidase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, the activity of the hexose monophosphate shunt and the concentrations of the pyridine nucleotides, especially NADPH, in X-ray-induced cataracts and the possible relationship of these parameters to the oxidation of protein sulfhydryls. (2) To isolate and characterize the crystallins (alpha and beta 3) which are released from high molecular weight proteins in X-ray-induced cataracts following treatment with disulfide-reducing reagents. Emphasis will be placed on amino acid composition, the significance of low tryosine content and to study any conformational changes in these proteins. (3) To study the nature of the high molecular weight protein and the possible role of sulfhydryl groups in the aggregation of proteins in human senile cataract.